1. Field of the Invention
The present invention relates to a method of forming a material layer for semiconductor manufacturing process, and more particularly, to a method of forming a dielectric layer for semiconductor manufacturing process.
2. Description of Related Art
Dielectric layers play an important role in semiconductor manufacturing process as they can isolate adjacent devices or metal lines from short circuit. In the conventional metal interconnection manufacturing process, the dielectric layer is deposited on the semiconductor substrate after the metal lines are formed. The plasma enhanced CVD (PECVD) is conventionally used for forming the dielectric layer. However, as semiconductor manufacturing process has come into the stage of deep sub-micron technology, the distance between metal lines shrinks considerably; thus, the conventional PECVD is no longer applicable for filling the dielectric layer into the gaps between the metal lines. Therefore, a High density Plasma Chemical Vapor Deposition (HDPCVD) process has been newly developed.
HDPCVD process has been widely applied in the field because it has the advantages such as good gap-filling capability, high quality of thin film and less metal contamination. HDPCVD process utilizes a high-efficiency plasma generator, such as Inductive Coupled Plasma (ICP), Electron Cyclotron Resonance (ECR) or helicon wave to generate high density plasma reactive source. In addition, a separate RF bias power supply can be applied to the wafer, such that the positive ions of the plasma will bombard the deposited film surface, thereby having the effect of eliminating voids and/or seams.
Along with the minimization of devices, the gaps between the metal lines become smaller and smaller while the aspect ratios thereof are higher and higher; thus, overhangs may be formed in the spaces between metal lines when HDPCVD process is applied. Voids may be formed when two adjacent overhangs are very close, such that the spaces between the metal lines can not be completely filled by the dielectric layer.